Design and Fabrication of an Array of Touch Sensors for Robotic Applications

Artificial tactile sensing is important for many robotic manipulation tasks such as environment exploration and object grasping. This paper presents a multilayer flexible force tactile sensor array. The sensor consists of two conductive electrodes spaced by an intermediate layer made from a double-sided tape. The intermediate layer has different-sized circular holes at the junctions of the top and bottom electrodes. Each sensing element of the sensor array works based on the on/off switching principle, which is activated based on the deformation of the element due to the touching force. The variation of the hole size allows the sensor to detect different external pressure levels. It is shown from the experimental results that the sensor can detect three different pressure levels in the range of 18.6-29.7 kPa, 35.6-71.2 kPa, and 60.8-77.5kPa. Moreover, we present a design of the sensor that eliminates the shadowing effect, which is caused by the formation of electric connections through unexpected paths in the sensor array causing the sensor's malfunction. Experimental results that verify the performance of the shadowing effect elimination and measurement of multiple contact locations were also presented. With the shadowing effect eliminated, our scanning method with row selection circuit and multiplexers reduce the number of electrodes while allowing measurement of multiple contact locations which is desirable for robotic applications.